Fuel systems, particularly those in automotive applications, typically incorporate a high pressure pump for pumping liquid fuel to an engine of an automobile. Some automotive fuel systems have one or more auxiliary feeds connected to the high pressure pump to supply fuel to locations other than the engine. As disclosed in U.S. Pat. No. 4,860,714 to Bucci, it is known to incorporate a jet pump in a supply side fuel line of the auxiliary feed to supply fuel to a reservoir of a fuel module. As a result, the high pressure pump needs to be sized to provide an adequate output of fuel to meet the fuel demand of the engine and the fuel demand of the auxiliary feed. As a result of diverting fuel away from the engine, inefficiencies may occur in the form of parasitic fuel flow losses, which may be of particular consequence if the fuel flow to the engine is compromised as a result of the fuel being diverted to the auxiliary feed, thereby reducing the running performance of the vehicle. This may be of particular importance during a cold weather start-up condition of the engine. Typically, a high pressure fuel pump driven by an electric motor powered by a battery of the vehicle has a reduced fuel output potential during the initial stages of a cold weather start-up, and therefore, it is generally necessary to have an oversized high pressure fuel pump to ensure that the engine receives the necessary amount of fuel to start up in cold weather. Otherwise, if the engine does not receive the necessary amount of fuel during the initial starting procedure, the engine may stall or even not start, and thus be hindered from starting and warming up.
Inefficiencies within a fuel system resulting from diverting an excess flow of fuel from the engine to an auxiliary feed sometimes results from the necessity to provide an oversized jet nozzle in the jet pump to prevent contamination from clogging or restricting flow of fuel through the auxiliary feed. Accordingly, the high pressure fuel pump may be required to have an inefficiently sized output capacity to meet the excess fuel demand of the auxiliary feed, thereby resulting in inefficiencies with the fuel system.